Logging in from phone

I have a new phone, have downloaded the app, but can't sign in. I am using the same username and password I use to log in on my computer, but it keeps saying "Member name or password mismatch" - what am I doing wrong? I know the details are correct as I have logged on with my computer this morning using the same details.

I am trying to find a good calorie counter that will work with data from my Apple watch. Specifically, I am trying to have the calories burned from my watch automatically sync with FatSecret so that I ...